The present invention relates to a human-body-contact, protective and cushioning interface structure. More particularly, it relates to such a structure which is designed to be interposed the body and some external structure which is worn on or attached to the body, and through which various kinds of loads (such as shock, general wearing-pressure related, and gravitational) may be applied to the body. While there are many applications wherein the structure of the present invention can offer distinct advantages, one preferred embodiment of the invention is described herein specifically (for illustration purposes) in the setting of a helmet, such as a military helmet, with respect to which the invention has been found to furnish particular utility.
Describing the invention first with reference to the conventional “military helmet” environment, this environment is very demonstrative of the issues that are successfully addressed by the present invention. For example, the current U.S.-issue infantry helmet utilizes an internal webbing system combined with a removable leather liner to suspend the helmet on the wearers head. Airspace between the webbing and the shell of the helmet greatly contributes to the ballistic and cooling capabilities of the helmet, but the webbing system has proven consistently to be quite uncomfortable, and thus to be the source of many complaints from users.
Generally speaking, such discomfort comes about principally because of localized capillary circulation loss caused by localized high-pressure points that exist in the contact interface between the helmet and the head. These pressure points come about typically because of poor conformation (uneven pressure distribution) of the usual web-borne head-contacting structure and the shape of the head. Such pressure points generate the complained-of discomfort and pain by creating localized low-blood-concentration ischemia regions in the head.
The structure of the present invention offers improvements in many areas of body-protective interest. This structure, in one preferred form of the invention, features a novel, multi-layered, pad-like cushioning structure which includes different layer components that individually address (1) conformance-comfort and ballistic behaviors, (2) moisture-wicking and cooling behaviors, and (3) moisture (water)-barriering behavior that both guards and enhances the performances associated with matters (1) and (2).
The structure of the invention, in relation to the matters of ballistic behavior and comfort, effectively minimizes, substantially to beyond notice, localized high-pressure contact conditions which are the principal creators of discomfort. In the bargain, so-to-speak, of dealing with this issue, the same structural features which vanquish discomfort promote significantly improved ballistic response. Notably, the structure's improved ballistic behavior remains uncompromised even in the very challenging circumstances of water immersion which can, if not carefully prevented from introducing any water into the cushioning core material, appreciably disable the shock-handling capabilities of that material.
Other features of the invention successfully improve the state of the art with respect (a) to minimizing the build-up of heat, (b) to maximizing the dispelling of perspiration, and (c) to enhancing the action of evaporative cooling.
According to one preferred embodiment of the invention, our proposed new structure includes (a) an outer body-contacting structure which is formed of a suitable moisture-wicking structure, (b) an anatomically conforming, acceleration-rate-sensitive (preferably viscoelastic), cushion-like core structure which is disposed adjacent the moisture-wicking structure, and (c) a moisture (water)-barriering, yet core-breathability-accommodating, barrier structure forming a substantially complete jacketing enclosure, or container, around the core structure.
The cushion-like, rate-sensitive core structure can be, selectively, either of a single-component or of a plural-component (plural sublayers) nature, and in the setting of a military helmet, preferably takes the form of two, individual, viscoelastic sublayers which have two different durometers. In this helmet setting, and during use by a wearer, the lower-durometer sublayer is employed closer to the head, and the higher-durometer sublayer is on the opposite side of the lower-durometer sublayer relative to the head, and is interposed the lower-durometer sublayer and the outer external structure which is still on the inside of a helmet. Within, and throughout the full, three-dimensional boundaries of each rate-sensitive, viscoelastic layer, the layer material therein is unfettered in its uniform, omnidirectional performance in response to introduced impact/shock loads. No other structure extends as a non-“homogeneous” anomaly through and in this region, which other structure would alter such uniform, all-over, load-response behavior.
In this newly proposed layered structure, the body-contacting (head-contacting in the case of a helmet) moisture-wicking layer effectively draws moisture away from the body. It accomplishes this, in the helmet environment, in a way which is experienced as being superior to the related activity of a conventional helmet support system.
The barrier layer forms a substantially uninterrupted continuum—a continuum which possesses no through-flow passage capable of permitting the through-flow of water to the core structure—enclosing the inside rate-sensitive core-structure material, and thus defines a limiting boundary for the migration of wicked moisture (water), preventing it from wetting the rate-sensitive material, and encouraging, at its outer surface, rapid evaporation and attendant cooling. In addition, the barrier layer is designed to accommodate substantially uncompromised cushioning behavior in the adjacent rate-sensitive, viscoelastic structure. This barrier layer, as above mentioned, may take the form of a suitable enveloping enclosure, or container, which may, as in the preferred embodiment of the invention specifically illustrated herein, be structured as a sprayed-on coating.
The cushioning, rate-sensitive, viscoelastic layer structure (two sublayers in the preferred helmet embodiment described herein) furnishes a unique and very effective response both to static and to dynamic (shock/impact/ballistic) loads. This material is temperature and pressure sensitive, and tends to creep (flow laterally) away from hot spots and from localized high-pressure spots. It thus tends to evenize the distributed static (wearing) load, and thus to eliminate, substantially, localized capillary circulation loss, and hence, localized ischemia regions. This latter-mentioned feature can be especially significant also in tight bandaging situations.
Additionally, and very significantly with regard to shock protection, the cushioning layer in the structure of this invention responds (rate-resistantly) to shock-produced, rapid acceleration with a resistance to deformation that generally rises in a somewhat direct relationship to the level of acceleration. This kind of acceleration-rate sensitivity is somewhat analogous to the phenomenon known in the world of fluid mechanics as shear-resistant fluid dilatancy. This behavior causes a shock load to be transmitted to and borne by the body over a relatively wide surface area, and thus generally reduces the likelihood of serious injury. The rate-sensitive core material proposed by the structure of this invention also responds to (and following) an impact event by recovering slowly to an undeformed condition—thus avoiding any dangerous “rebound” activity. The important and special rate-resistant, and slow “recovery”, response of this material requires the maintenance, immediately adjacent it, of adequate gas-breathability during onset and recovery from deformation, in an environment which also simultaneously guards the core material against the infusion of water, or other “solid-like” moisture. Moisture infusion would dramatically and negatively affect ballistic-response cushioning behavior. The barrier layer, either as an enclosure with some space existing between it and the core structure, or as a sprayed-on layer which possesses the quality of gas breathability, accomplishes these functions.
The layer structure of this invention is easily rendered in a variety of specific configurations, and thus is readily usable in a host of different settings. It is relatively easy and inexpensive to manufacture, and it can be introduced very conveniently in a wide range of “retrofit” situations. The specific layer organization of the invention which is chosen for different selected applications is itself an accommodating variable—a variable which enhances the invention's versatility. For example: overall structure thickness can be different for different circumstances. A single, or more than two, rate-sensitive sublayer(s) can be employed. Within a relatively wide range, a different specific durometer value (or values) for the rate-sensitive sublayer(s) can be chosen. The moisture-wicking layer can be distributed in different ways in the structure to suit different use environments, and can be omitted if desired for use of the invention in certain applications. The moisture (water)-blocking barrier layer can have different selected characteristics to suit different applications. Importantly, this layer is chosen to be such, that in any situation, such as a water-immersion event, which exposes the proposed new layer structure to significant wetting, substantially no water can penetrate the barrier layer to degrade the shock-managing performance of the rate-sensitive layer material contained inside.
Accordingly, variations from, and modifications of, the invention are recognized to be possible. Several of these are mentioned specifically below.
All of the special features and advantages mentioned above that are offered by the present invention will become more fully apparent as the description which now follows is read in conjunction with the accompanying drawings.